1. Field of the Invention
The present invention relates to a projector, and more particularly to a projector equipped with a light modulation device utilizing a grating and liquid crystal filled in the grooves of said grating or a grating of refractive index distribution generated in liquid crystal (both types being hereinafter collectively called GLC (grating liquid crystal)).
2. Related Background Art
Projectors utilizing liquid crystal device are already disclosed in the U.S. Pat. Nos. 4,864,390 and 4,962,997, and in the U.S. patent application Ser. No. 147,519, now U.S. Pat. No. 4,989,076, of the present applicant.
On the other hand, the GLC device is already known. The present applicant already disclosed the GLC device and its applications in the U.S. Pat. Nos. 4,729,640, 4,822,146, 4,850,681 and 4,856,869 and in the U.S. patent application Ser. No. 216,127, now U.S. Pat. No. 5,122,888. Similar devices were also disclosed in the Japanese Laid-open Patents Sho54-111846 and Sho55-21001.
Among these references, the last two disclosed projectors equipped with a GLC device and a Schlieren optical system, but either utilizes a single device and forms a diffraction grating from a grating of refractive index distribution generated in the liquid crystal.
Two- or multi-color image display with a single liquid crystal device generally requires a mosaic filter on said device, so that the efficiency of light utilization is not too high. The liquid crystal device may be illuminated with a cathode ray tube as proposed in the Japanese Laid-open Patent Sho54-111846, but such solution is undesirable as the apparatus becomes bulky.